Apparatus that generate three-dimensional objects, commonly referred to as “3D printers”, have been proposed as a potentially convenient way to produce three-dimensional objects. These apparatus typically receive a definition of the three-dimensional object in the form of an object model. This object model is processed to instruct the apparatus to produce the object using one or more material components. This may be performed on a layer-by-layer basis. There are many different types of such apparatus. The processing of the object model may vary based on the type of apparatus and/or the production technology being implemented.